Fiber in Animal Nutrition

Fiber in Dog and Cat Food 62 well formed when cellulose with 200–300 µm length was added to the fiber-free diet at 10%of the dietary dry matter.The beneficial effect of cellulose was associated with an increase in the dry matter content of feces from about 28 to 32%. Cats fed ground chicken carcass supplemen- ted with a pre-mix produced feces with a dry matter content of 45% (Fekete et al., 2004). Mixing the fiber-free diet with cellulose-rich peanut hulls (to a crude fiber level of 7.7% in the dietary dry matter) raised fecal dry matter content to almost 50%. Kienzle et al. (1991) reported on the feeding of a fiber-free mixture of beef shoulder muscles, minerals and vitamins without or with 10% added cellulose. Calculations on the basis of the presented data showed that cellulose addition markedly expanded the dry matter fraction of feces. The two publications (Fekete et al., 2004; Kienzle et al., 1991) did not mention diarrhea for the cats fed the fiber-free diets. The addition of high amounts of cellulose to wet, meat-based foods tends to decrease gastrointestinal transit time in beagle dogs (Burrows et al., 1982; Lewis et al., 1994).This points at more peristaltic waves in the small and large intestine. However, the outcomes of dog studies on cellulose-induced myoelectric gut activity (Bueno et al., 1981; Burrows and Merritt, 1983; Burger et al., 2006) are difficult to reconcile with faster intestinal transit rate. 5.2.2 Cellulose as caloric diluter Light foods are recommended for weight maintenance in overweight-prone animals. The energy content of light foods for dogs and cats is about 15% less than that of com- parable, regular products. The amount of crude fiber in light dry foods ranges from 4 to 12% crude fiber. Veterinary weight- reduction dry diets for obese animals may have up to 22% crude fiber. On a weight basis, cellulose provides an amount of heat of combustion (gross energy) similar to that of starch, but its available (me- tabolizable) energy content is negligible.Thus, cellulose can be used as caloric diluter for the production of light and weight-reduction foods. Formulating low-calorie foods is very difficult when using conventional ingredients without cellulose. Cellulose is a polymer of glucose units bonded by β 1,4-linkages which means that it cannot be hydrolysed by pancreatic α -amylase in dogs and cats. Ingested cellulose is only broken down and fermented in the colon by microbial enzymes, but this con- cerns only a very small fraction of cellulose so that little energy is generated in the form of short-chain fatty acids. The indigestible and poorly fermentable nature of cellulose is illustrated by the experimental results of Kienzle et al. (2001). Dogs were fed three basic diets consisting of poultry meal, lard and a vitamin-mineral mixture without or with corn starch. To each diet, containing about 1% crude fiber in the dry matter, cellulose was added to reach crude fiber concentrations of 7, 15 or 20%. For the 12 diets there was a direct relationship between crude fiber intake and fecal excretion when expressed as g per kg body weight.The regression line did not differ from y = x so that the amount of cellulose ingested was fully recovered in feces. When feces of dogs or cats was used as in- oculum source to determine in-vitro fermen- tation of fibrous substrates, organic matter disappearance and short-chain fatty acid production was negligible when cellulose instead of other fibrous substrates was used (Sunvold et al., 1995a,b; Barry et al., 2011). © ERLING Verlag